John had mentioned these kings (rulers, presidents, prime ministers, etc.) in Revelation 17:2. They seek their sense of well being not in the Creator who gave them their high position but in some creature—thus, spiritual adultery. Further, as heads of the beast (Revelation 17:9–10) upon which the great prostitute is seated (she is its mistress), the kings are complicit with the woman in enticing all nations to seek their happiness in creatures, and so be unfaithful to the heavenly Spouse.
3 For all nations have drunk the wine of the passion of her sexual immorality, and the kings of the earth have committed immorality with her, and the merchants of the earth have grown rich from the power of her luxurious living.”